I think it is a matter of a Criminal Record more than an impaired driver.
It is my understanding that DUI or DWI is treated in Canada to be a more serious offence than it is in the USA. I'm not sure if you are suggesting that the refusal of entry may be related to criminal offences other than drinking offences or not. As I am not a lawyer I certainly do not understand the technicalities involved here.
I do know that the first time I was at an outfitters and he had clients refused entry they told the outfitter specifically the refusal was related to a prior drinking offence. Since the first time I believe I have heard of two other such instances from outfitters. The outfitters tell me they advise their potential clients to check with border officials prior to arriving if they have any criminal(?) background and usually specifically mention to the potential client about prior drinking convictions.
It is on this background that I based my comments.
Jim
